HiFiman He-400/ Sennheiser HD 598 Desktop DAC/AMP ~$200??

I need to get a more powerful DAC/Amp for my HiFiman HE-400's and my Sennheiser HD598's. Right now I'm using the FiiO E7 DAC/Amp and it works fine, but I am 100% sure that I could get much better for a ~$200 price. I'm looking at the Audioengine D1 and the FiiO E17/FiiO E9K (Paired) to power these headphones. Anyone know how they sound with these 2 headphones?